1. Field of the Invention
The invention relates to devices for selectively coupling a first item to a moving second item for movement therewith. More particularly, the invention relates to a coupling device for selectively coupling and uncoupling a load bearing unit to a moving flight of a link chain conveyor.
2. Discussion of the Prior Art
Examples of various coupling devices for selectively coupling a load bearing unit, such as a pallet and the like, to a conveyor shown in:
U.S. Pat. No. 2,918,020 PA1 U.S. Pat. No. 3,032,173 PA1 U.S. Pat. No. 3,045,610 PA1 U.S. Pat. No. 3,048,126 PA1 U.S. Pat. No. 3,194,177 PA1 U.S. Pat. No. 3,196,807 PA1 U.S. Pat. No. 3,390,641 PA1 U.S. Pat. No. 3,467,025 PA1 U.S. Pat. No. 3,618,532 PA1 U.S. Pat. No. 3,648,618 PA1 U.S. Pat. No. 3,874,302.
The various coupling devices proposed by the above-listed U.S. Pats. are relatively complicated, which makes them expensive to make and maintain in operation.
U.S. Pat. No. 4,438,702, issued to Arthur B. Rhodes on Mar. 27, 1984, teaches a simple, straightforward coupler device which has some features in common with the coupler device of the present invention. The coupler device of this patent includes a conveyor chain engaging pin attached to a load bearing unit for longitudinal movement between a lowered, conveyor chain engaging position whereat the depending end of the pin engages the links of the conveyor chain, and a raised, conveyor chain disengaged position whereat the free depending end of the pin is removed from engagement with the links of the conveyor chain.
While this coupler device works extremely well, it has been observed that in some situations after long use, that apparently due to wear of the pin or the conveyor chain, or a stack-up of manufacturing tolerance between the pin and conveyor chain, the pin can slip off-center relative to the longitudinal axis of the chain. This off-center condition of the pin when inserted in a chain link can cause lateral forces or movement forces to be applied to the pin sufficient to interfere with the movement of the pin between the lower engaged position and raised disengaged position. Further, it has also been experienced that from time to time in some installations that when the pin is in the raised disengaging position, the conveyor chain may make brushing contact with the depending pin end. This condition can generate noise as well as wear of the pin and conveyor chain.